Packers are commonly used in the oil and gas industry for sealing an annulus in a well bore. The annulus might exist, for example, between the well bore liner and the production tube.
Each packer generally comprises an elastomeric sealing element which, when axially compressed, expands radially outwards from a mandrel into engagement with, for example, a well bore wall.
There are drawbacks associated with some conventional packers. For example, it is known for the seal between the packing element and the casing to fail if the element has been set in a high temperature environment which subsequently cools. It is also known for the seal to fail when the packer is subject to setting backlash reducing the pressure on the sealing element.
Furthermore, packers “self-set” when there are very high flow rates flowing past an unset packer. This problem is exacerbated if the fluid can flow between the packing element and the mandrel to which it is mounted.